[R] prop.test question

[Thomas Subia]

Colleagues
Consider:smokers  <- c( 83, 90, 129, 70 )
patients <- c( 86, 93, 136, 82 )
prop.test(smokers, patients)
    4-sample test for equality of proportions
    without continuity correction

data:  smokers out of patients
X-squared = 12.6, df = 3, p-value = 0.005585
alternative hypothesis: two.sided
sample estimates:
   prop 1    prop 2        prop 3        prop 4 
0.9651163 0.9677419 0.9485294 0.8536585 

Now:prop.trend.test(smokers, patients)    Chi-squared Test for Trend in Proportions

data:  smokers out of patients ,
 using scores: 1 2 3 4
X-squared = 8.2249, df = 1, p-value = 0.004132
How can one determine the direction of the trend?
Thomas Subia




	[[alternative HTML version deleted]]